Process for the preparation of hydriodic acid



airs STATES GEORGE B. FRANKEORTER, OF THE UNITED STATES ARMY.

rnocnss non THE'IREPVARATION or HYDRIODIC non).

ieeonsi.

No Drawing.

Specification of Letters Patent.

- Application filed June 4, 1919. SerialNo. 501,802.

Patented June 7, 1921.

(FILED UNDER THE AGT OF MARCH 3, 1883, 22 STAT. In, 625.)

T 0 all whom it may concern: Be it known that I, GEORGE B. FRANK-ronrnn, of the U. S. Army, a citizen of the United States, stationed atlVashington, l). 0., have invented an Improvement in Process for thePreparation of Hydriodic driodic acid, either as the pure dry gas or asthe aqueous solution. As is wellknown, hydriodic acid can not bemade'satlsfactorily by treating an iodid with sulfurlc acid as in thecase of the preparation of hydrochloric acidfrom a chlorid and sulfuricacid. This is on account of the powerful reducing properties of theacid. Thus, when an iodid, for example, potassium iodid, is treated withsulfuric acid, some hydriodic acid is liberated but in addition to theacid some iodin is set free. At the same time hydriodic acid, on accountof its powerful reducing power, reacts wlth the sulfuric acid changingsome of it to sulfurous acid and some to hydrogen sulfid. As a result ofthis reduction, the yield of hydriodic acid is very small and the acidis very impure. The preparation of hydrlodlc acid must therefore, beother than the analogous method for the preparation of hydrofluoric orhydrochloric acids.

Several methods have been used for the preparation of hydriodic acid.All of them, however, have some objectionable features; either theprocess does not give a pure product and a good yield or it is tooexpensive and the apparatus too complex for satisfactory economicproduction. My process eliminates these objections.

It was found in Working with the terpenes such as commercial pinene,usually termed common pinene or with rosin oil, that when iodin isbrought in contact with them, even at the ordinary temperature, avigorous reaction takes place between the organic compound and the iodinforming hydriodic acid and an iodo-compound of the organic substance.The latter on standlng oron heating breaks ofi hydriodic acid and acondensed form of theorganic substance is formed. There actionmay berepresented by the following typical equation v In certain cases, thereaction isnot so simple as the above and some of the iodin is heldcombined with the organic substance. In cases where iodin is held as adefinite compound, it is necessary to heat the substance in order toliberate the iodin as the acid. In a few cases the reaction is so vio- Ylent as to produce an explosion.

To prepare hydriodic acid by my process, a

certain amount of the active reagent is placed in a generating flaskconnected with a condenser and iodin cautiously allowed to drop into it.As soon as the iodin comes in contactwith the reagent, hydriodic acidgas is rapidly liberated passing over into the condenser as heavy whitefumes. Thesefumes consisting of the moist acid are passed through a tubecontaining redjphosphorus to remove any free iodin which may'have beencarried over by the acid. The purified gas thus formed may be eithercondensed, used in the gaseous state or passed into water to form theaqueous solution. If the temperature is properly regulated, theliberation of gas may be easily controlled. The

iodin may be added either as the solid or in solution.

In addition to the terpenes, other hydrocarbons,'for instance, hexylene,and more especially'the unsaturated ones react in similar manner.Certain oxy compounds also react with iodin as, for example, thealdehydes and alcohols and more especially the unsaturated ones. Whilethe unsaturated hy-,

drocarbons and oxy compounds are especlally adapted to this reaction itis to be understood that the invention is not limitedtothe use of theunsaturated form but that the saturated form may also be used.

Having thus described my process for the preparation of hydriodic acidby bringing iodin in contact With certain organic compounds, either atroom temperature or at higher temperature, What I claim and desireprotection in by Letters Patent is 1. A simple continu us p e s. for thepreparation of hydriodic acid by bringing iodin in contact With. commonpinene and subsequently removing all of the hydriodic acid bydistillation. Q

2. A process of making hydriodic acid by bringing pure iodin in contactwith rosin oil and subsequently removing the hydriodic.

by heating an alcohol with iodin and subsequently removing the hydriodicacid formed by heating. q

6. A process of making hydriodic acid by bringing iodin in contact witha terpene and removing the hydriodicacid from themixture by heating.

f 7 'A process of making hydriodicacid by bringing iodin in contact withan unsaturated oxycompound, removingthe hydri' ocllc acid from the mxture by heating and removing impurities from the acid.

8. A process of making hydriodic acid by placing a terpenein areceptacle, adding "odin to the terpene and collecting thehydriodicacidgas given off. I it p 9 A process of making hydriodic acid by placing aterpene in a receptacle, adding iodinto the terpene, removing thefreeiodin from the hydrioclicncid gas given oil and collecting the gas.

10. A process of making hydriodic acid by placing a terpene in areceptacle, adding iodin to the terpene and passing the hydriodic acidgas given 0E over red phosphorus to remove the free iodin.

11. A process of making hydriodic acid by placing an unsaturatedhydrocarbon in a receptacle, adding iodin, and collecting the gas givenoff. V

12. Aprocess of maklng hydrlodlc acid by placing an unsaturatedhydrocarbon in a receptacle, adding iod n, removing the free iodin fromthe hydriodic acid gas given off 7 and collecting the gas. 13. A processof making hydriodic acid, by placing'an. unsaturated hydrocarbon in areceptacle, adding iodin, passing the hy driodic acid over redphosphorus to remove impurities and collecting the gas.

let. A process of making hydriodic acid by placing an unsaturatedoily-compound in a receptacle, adding iodin, removing the impuritiesfrom the resulting ng the gas given off.

15. A process of making hydrlodic acid gas and collectplacing anunsaturated oxy compound in a receptacle, adding iodin thereto,removingthe free iodin from the hydriodic acid gas given 0E andcollecting the gas;

. 16. A'process of, making hydriodic acid placing an unsaturated;oXy-com'pound in a receptacle,'adding iodin, passing the hydriodic acidgas given of]? over red phosphorus to remove impurities and collectingthe; gas. a p

l7. Aprocess of making hydriodic acid by slowly adding iodin .to anunsaturated hydrocarbon and collecting the hydriodic acid-gas given off.7 V

GEORGE B. FRANKFORTER.

